PDF Highlighting tool

Earlier I talked about few tools for editing PDF files (for free) on
linux. You can go through the discussion here. I recently came across
some more free tools that tend to make our life little easier,
particularly when it comes to editing pdf files on linux. Some of
these tools are as follows:

Scribus : Limited capabilities
Inkscape : Limited capabilities
Okular : Limited capabilities. You can do some highlighting and add
annotations. But they don't seem to be very neat. Just give a look at
some screenshots.
PDF-xchange-viewer. Its a windows based application which is free to
download at present and can be run on linux using Wine. I could use it
flawlessly on my Ubuntu Intrepid Ibex (8.10). Among all pdf editing
tools, this seems to the best option for editing pdf files. Even
though its not a native linux application, it is better than going
back to windows just for editing a PDF file. However, I am still
waiting for GNUpdf which, I believe, would provide a permanent relief
to linux users in this regard.

To get started, first use synaptic packet manager to install wine. For
Ibex, follow the instructions given at this link. Download
PDF-xchange-viewer from its website and run it using wine. That's all.
It installs itself within a folder. A screenshot of PDF-xchange-viewer
is shown in the adjacent thumbnail. Its really neat and close to what
we find in Adobe Acrobat PDF editor.
PDFescape: You can edit PDF files online (particularly fill up forms)
at this website. This is useful if you are in a hurry and can't
install a PDF editing software on a public machine.